The strategic goal of this research is to improve scientific understanding of coral reef ecosystems throughout the Pacific, and serve as the basis for improved conservation and resource management. The recent designation of the Pacific Remote Islands Marine National Monument highlights the importance of this research.

With their extremely isolated location, many of the Pacific Remote Island Areas host a vibrate marine ecosystem.Previous Pacific RAMP cruises have documented relatively high coral cover and diversity; and high densities of large-bodied reef fish including large numbers of apex predators such as Grey Reef Sharks (Carcharhinus amblyrhynchos) and Scalloped Hammerhead sharks (Sphyraena lewini). Many of these apex predators are rare near human population centers. AS in previous years, this Pacific RAMP cruise will perform a suite of standardized multi-disciplinary methods which include Rapid Ecological Assessments (REA) for fish, corals, other large invertebrates, and algae; towed-diver surveys for large-bodied fish and habitat composition; and oceanographic studies, which include the measurement of conductivity, temperature, and density of the water column (CTD casts); water sampling; and deployment of sea-surface temperature (SST), subsurface temperature recorders (STR) and acoustic doppler current profilers (ADCP).Scientists will also be deploying Ecological Acoustic Recorders (EARs) to learn about changes in the presence and activity of marine mammals, fish, crustaceans and other sound-producing marine life when researchers aren't there to record it otherwise. Autonomous reef monitoring structures (ARMS) will also be deployed as part of the CReefs project. ARMS are simple, standardized collecting structures designed to roughly mimic the structural complexity of reef habitats.They allow for the identification of small, hard-to-sample, but ecologically important cryptic invertebrates. ARMS are being utilized throughout the Pacific and globally to systematically assess spatial patterns and temporal changes ofbiodiversity.Use of the EARS and ARMS are an exciting addition to RAMP data collection efforts.

Follow along below to learn more about where we are going, what we are seeing, and what we have found ...

Sunday, March 14, 2010

The Oceanography Team

by Oliver Vetter

Frank Mancini and Oliver Vetter using a liftbag to deploy the Remote Access Sampler
(Photograph by Noah Pomeroy)

As part of our Pacific RAMP cruises, several types of oceanographic instruments are deployed to continually measure water conditions at our research sites. These instruments remain in place for a period of 2 years and are maintained during each cruise. To accomplish this, the oceanography team’s daily operations typically include deploying and recovering oceanographic instruments. These can be small, like the numerous subsurface temperature recorders we’ve deployed, or larger like a wave and tide recorder or sea surface temperature buoy. The larger instruments require the installation of large anchors to hold them to the sea floor under strong currents and waves. The anchors we typically use are 250lbs, which are obviously too heavy for a single person to carry either above water or below. To deploy these anchors we use lift bags, which are basically bags filled with air that float the anchor when full. At the surface the bag is full and the diver slowly releases air out of the bag until the weight of the anchor, being pulled down by gravity, equals the upward buoyancy of the lift bag. At this point the bag can be submerged and starts to slowly descend to the sea floor, preferably under the control of the oceanographer. Since the water pressure increases with depth as you descend through the water column the additional water pressure compresses the volume of the lift bag and so reduces its buoyancy. This causes the anchor to sink faster and in turn reduce the buoyancy and sink even faster, so air has to be slowly added again and again to keep the lift bag from dropping too quickly and out of control. This can be a tricky balance of releasing and adding air, to drop the anchor under control to the seafloor.

Once at the bottom, the new instrument is clamped to the anchor and the old instrument and anchor are removed in the same, but opposite way; the air bag is refilled, and the anchor is raised from the bottom. This time the oceanographer has to be particularly careful not to raise the anchor too fast, or let it get out of control. When diving shallower than 130 feet on normal SCUBA, the diver should ascend at a rate no quicker than 30 feet per minute to avoid decompression sickness. With proper training this kind of work is safe and it’s a matter of pride among the oceanography team to get a good lift.

In the picture, Oceanographers Oliver Vetter and Frank Mancini are retrieving a Remote Access Sampler (RAS), an instrument that can be programmed to collect water samples at predetermined intervals. This RAS was programmed to collect water samples every hour through out a 48-hour period at Rose Atoll. The water samples will be analyzed for Dissolved Inorganic Carbon and Total Alkalinity in an effort to understand the water chemistry of the reef throughout the day. This is part of a larger effort to understand and predict the ecological impacts of ocean acidification.

1 comment:

Since NOAA has been monitoring the Atolls and reefs in and around American Samoa for several years. Have any Remote Access Samplers or other equipment been set on or near the reefs to be retrieved on this expedition? If so what data is collected. PS: I especially liked this Diver picture Frank M. Jr.

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The mission of the Coral Reef Ecosystem Division is to provide sound science to enable informed and effective implementation of ecosystem-based management and conservation strategies for coral reef ecosystems of the U.S.-affiliated Pacific Islands Region.

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